The present invention relates generally to the field of carbon dioxide removal. In particular, the present invention relates to the removal of carbon dioxide using molecular sieves.
Exposure to carbon dioxide (CO2) for extended periods of time can be harmful to the health of humans and other mammals. Thus, a carbon dioxide concentration level of less than approximately 1% is typically maintained in enclosed environments, such as submarines, spacecrafts, or space suits. Current methods of removing carbon dioxide from the air include using solid carbon dioxide sorbents including, but are not limited to: soda lime, zeolites, molecular sieves, solid oxides, alkali metal carbonates, alkali metal hydroxides, amines, and combinations thereof. A specific example of a carbon dioxide removal system using an amine as the sorbent is discussed in U.S. Pat. No. 6,364,938 (assigned to Hamilton Sundstrand Corporation), which is incorporated herein by reference.
Molecular sieve carbon dioxide removal systems currently used in the art typically contain sorbent beds for removing water and carbon dioxide. The sorbent beds are regenerated after the beds are saturated by using embedded electrical heaters. The sorbent beds typically operate in an adiabatic mode without any integral or active cooling. As a result, the sorbent beds operate at elevated temperatures, with a negative effect on adsorption isotherms. One method of mitigating this effect is by integral cooling of the sorbent beds. However, this increases the complexity of the carbon dioxide removal system.
There is a need in the art for a carbon dioxide removal system which operates substantially isothermally and at ambient temperature.